Who said "Pain is part of the path to mastery."?

This quote is attributed to Iron Fist.

Pain is part of the path to mastery. - Iron Fist

"Pain is part of the path to mastery."

Iron Fist Perseverance

"I am the living weapon. I am Iron Fist."

"I've trained my entire life for this moment."

"The chi flows through all living things."

"I need to protect the innocent."

"Perseverance is the key to success."

"Don't give up on what you believe in."

"I've been through worse."

"You learn to live with the pain."